. >> reporter: a team of fbi investigators has arrived here in benghazi. they're gogt to now begin sifting through the rebel and ashes at the u.s. consulate to identify any clues or evidence that may help them in identifying who is behind the attack that killed the u.s. ambassador and three other americans. we also understand that the libyan government for their part is cooperating with the u.s. intelligence agencies and other agencies involved in the investigation. the libyan government believes that this was a preplanned attack, that this was not a spontaneous outburst of violence as some have suggested. so far they have four individuals in their custody. they say several more are under surveillance. they are trying to see whether these individuals have any important information that can benefit the american investigation. meanwhile, u.s. intelligence assets including unmanned aerial drones are keeping an eye above the skies of benghazi and eavesdropping on the people below to see if there's any communication that could also shed some light onto tuesday'